Root Trying to downgrade to 1.5 and getting 'Model ID Incorrect'

Hi all

Using instructions from here:

Full Update Guide - MT3G/Magic Firmware to CyanogenMod - CyanogenMod Wiki

To downgrade my Vodafone UK 32B Magic from 1.6 to 1.5 but after trying to HBOOT with the SAPPIMG.nbh provided, it gets so far then fails saying 'Model ID Incorrect'.

What am I doing wrong?

Thanks in advance